I have a rigged object that I want to cut in half and be able to move around, but the armature deforms it
One possible solution is animate your rig until you get to the point where you need it to split in two. When you get to that point, go into Object Mode, select the rig, Shift + select the character mesh that is bound to it, and then duplicate them both (Shift + d). You will have a copy of both armature and character mesh, which means all vertex weights will be inherited, as well as all keyframes, up to that point. Put an invisible material on the half of the new character mesh that you don't want to be rendered, and also put one on the opposite half of the old character mesh. When you add new keyframes to the new rig, it can look as if the character is splitting in two.